Leiomyosarcoma (LMS) is an uncommon malignant mesenchymal tumor. This tumor arises from smooth muscle cells and mostly occurs behind the peritoneum area, including pelvis and uterus. Oral LMS is exceedingly rare and occurs mainly in the bones and the soft tissues. It generally involves adults, without any considerable specific age or sex predominance. This tumor has a clinically aggressive growth pattern and is usually presented as a non-ulcerated, painless, destructive mass with a relatively firm consistency. LMS can be easily mistaken for other more common spindle cell lesions by only light microscopic evaluation; consequently, immunohistochemical study is helpful for the definitive diagnosis. The suggested treatment modalities include excision, radical surgery, radiation therapy, chemotherapy. Wide surgical resection is the most preferred treatment protocol. Herein, we report a clinically controversial case of gingival LMS in a 32-year-old female and also discuss the diagnostic procedures and treatment modalities in this malignancy.